This invention relates generally to the field of vision testing and more specifically to testing contrast sensitivity and multiple visual functions with a portable testing device and accessories.
Testing the functional capacity of the macula requires multiple measurements, for example, visual acuity, potential acuity, contrast sensitivity, glare impairment, vision distortion, color vision, and low vision. Unfortunately most patients do not receive this battery of test because many examiners do not have the needed equipment due to cost, space requirements for non-portable instruments, and the time required for testing with multiple devices.
Many contrast sensitivity tests are available and are used to measure the loss of contrast in patients with ocular diseases, such as, cataract and macular diseases. Arrays of symbols of varying size and varying contrast or sine wave patterns of varying frequencies and varying contrast are presented to a subject and the subject discerns the images until the image becomes to faint to decipher. The illumination level affects contrast sensitivity and brightness is a parameter requiring specification. Some commercially available devices for measuring contrast sensitivity are costly computer programs, such as, Medmont AT-20, Medmont International Pty. Ltd., Vermont, Australia and Mentor B-VAT II, Mentor Corp., Santa Barbara, Calif.; illuminated vision charts, such as, wall or stand mounted AC powered CSV-1000, Vector Vision, Greenville Ohio; and hand-held vision charts such as the externally illuminated Mars Letters Charts, Mars Perceptrix, Corp., Chappaqua, N.Y. There is currently no contrast sensitivity chart that is hand-held and internally illuminated. Internal illumination has the advantage of even light distribution and eliminating the influence of aberrant ambient light.
Glare testing currently involves the patient holding the Mentor BAT brightness acuity tester, Mentor Corp., Santa Barbara, Calif., and viewing a distance vision chart which required a examination lane with a projector and wall screen or the CSV-1000HGT (Halogen Glare Test) Vector Vision, Greenville Ohio that is mounted on a stand or wall and requires AC powered.
Color vision tests require a computer program or test plated viewed under special lamp that give the correct characters of the light.
Low vision testing requires magnifiers, special bright illuminating lamps, and a variety of vision testing charts.
The Retinal Acuity Meter or RAM® manufactured by AMA Optics, Inc. has helped to improve patient care by implementing a hand-held tester that is fast, easy and inexpensive, but it is limited to a single test, the potential vision test.
My invention of an internally illuminated and hand-held vision testing device that presents a battery of eye tests is time saving and overcomes many problems facing clinicians, such as, inefficient testing methods, costly investment in multiple instruments, large space requirements for non-portable instruments, and difficulties of controlling extraneous ambient light for test relying on externally illuminated. The simplicity of my time saving testing invention would likely encourage clinicians to perform more in depth testing and this could lead to improved health care.